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b94c6a7e38
putty-source/ssh1connection-client.c
Simon Tatham b94c6a7e38 Move client-specific SSH code into new files. 
This is a major code reorganisation in preparation for making this
code base into one that can build an SSH server as well as a client.

(Mostly for purposes of using the server as a regression test suite
for the client, though I have some other possible uses in mind too.
However, it's currently no part of my plan to harden the server to the
point where it can sensibly be deployed in a hostile environment.)

In this preparatory commit, I've broken up the SSH-2 transport and
connection layers, and the SSH-1 connection layer, into multiple
source files, with each layer having its own header file containing
the shared type definitions. In each case, the new source file
contains code that's specific to the client side of the protocol, so
that a new file can be swapped in in its place when building the
server.

Mostly this is just a straightforward moving of code without changing
it very much, but there are a couple of actual changes in the process:

The parsing of SSH-2 global-request and channel open-messages is now
done by a new pair of functions in the client module. For channel
opens, I've invented a new union data type to be the return value from
that function, representing either failure (plus error message),
success (plus Channel instance to manage the new channel), or an
instruction to hand the channel over to a sharing downstream (plus a
pointer to the downstream in question).

Also, the tree234 of remote port forwardings in ssh2connection is now
initialised on first use by the client-specific code, so that's where
its compare function lives. The shared ssh2connection_free() still
takes responsibility for freeing it, but now has to check if it's
non-null first.

The outer shell of the ssh2_lportfwd_open method, for making a
local-to-remote port forwarding, is still centralised in
ssh2connection.c, but the part of it that actually constructs the
outgoing channel-open message has moved into the client code, because
that will have to change depending on whether the channel-open has to
have type direct-tcpip or forwarded-tcpip.

In the SSH-1 connection layer, half the filter_queue method has moved
out into the new client-specific code, but not all of it -
bidirectional channel maintenance messages are still handled
centrally. One exception is SSH_MSG_PORT_OPEN, which can be sent in
both directions, but with subtly different semantics - from server to
client, it's referring to a previously established remote forwarding
(and must be rejected if there isn't one that matches it), but from
client to server it's just a "direct-tcpip" request with no prior
context. So that one is in the client-specific module, and when I add
the server code it will have its own different handler.
2018-10-21 10:02:10 +01:00

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/*
* Client-specific parts of the SSH-1 connection layer.
*/
#include <assert.h>
#include "putty.h"
#include "ssh.h"
#include "sshbpp.h"
#include "sshppl.h"
#include "sshchan.h"
#include "sshcr.h"
#include "ssh1connection.h"
void ssh1_connection_direction_specific_setup(
struct ssh1_connection_state *s)
{
if (!s->mainchan) {
/*
* Start up the main session, by telling mainchan.c to do it
* all just as it would in SSH-2, and translating those
* concepts to SSH-1's non-channel-shaped idea of the main
* session.
*/
s->mainchan = mainchan_new(
&s->ppl, &s->cl, s->conf, s->term_width, s->term_height,
FALSE /* is_simple */, NULL);
}
}
typedef void (*sf_handler_fn_t)(struct ssh1_connection_state *s,
int success, void *ctx);
struct outstanding_succfail {
sf_handler_fn_t handler;
void *ctx;
struct outstanding_succfail *next;
/*
* The 'trivial' flag is set if this handler is in response to a
* request for which the SSH-1 protocol doesn't actually specify a
* response packet. The client of this system (mainchan.c) will
* expect to get an acknowledgment regardless, so we arrange to
* send that ack immediately after the rest of the queue empties.
*/
int trivial;
};
static void ssh1_connection_process_trivial_succfails(void *vs);
static void ssh1_queue_succfail_handler(
struct ssh1_connection_state *s, sf_handler_fn_t handler, void *ctx,
int trivial)
{
struct outstanding_succfail *osf = snew(struct outstanding_succfail);
osf->handler = handler;
osf->ctx = ctx;
osf->trivial = trivial;
osf->next = NULL;
if (s->succfail_tail)
s->succfail_tail->next = osf;
else
s->succfail_head = osf;
s->succfail_tail = osf;
/* In case this one was trivial and the queue was already empty,
* we should make sure we run the handler promptly, and the
* easiest way is to queue it anyway and then run a trivials pass
* by callback. */
queue_toplevel_callback(ssh1_connection_process_trivial_succfails, s);
}
static void ssh1_connection_process_succfail(
struct ssh1_connection_state *s, int success)
{
struct outstanding_succfail *prevhead = s->succfail_head;
s->succfail_head = s->succfail_head->next;
if (!s->succfail_head)
s->succfail_tail = NULL;
prevhead->handler(s, success, prevhead->ctx);
sfree(prevhead);
}
static void ssh1_connection_process_trivial_succfails(void *vs)
{
struct ssh1_connection_state *s = (struct ssh1_connection_state *)vs;
while (s->succfail_head && s->succfail_head->trivial)
ssh1_connection_process_succfail(s, TRUE);
}
int ssh1_handle_direction_specific_packet(
struct ssh1_connection_state *s, PktIn *pktin)
{
PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
PktOut *pktout;
struct ssh1_channel *c;
unsigned remid;
struct ssh_rportfwd pf, *pfp;
ptrlen host, data;
int port;
switch (pktin->type) {
case SSH1_SMSG_SUCCESS:
case SSH1_SMSG_FAILURE:
if (!s->succfail_head) {
ssh_remote_error(s->ppl.ssh,
"Received %s with no outstanding request",
ssh1_pkt_type(pktin->type));
return TRUE;
}
ssh1_connection_process_succfail(
s, pktin->type == SSH1_SMSG_SUCCESS);
queue_toplevel_callback(
ssh1_connection_process_trivial_succfails, s);
return TRUE;
case SSH1_SMSG_X11_OPEN:
remid = get_uint32(pktin);
/* Refuse if X11 forwarding is disabled. */
if (!s->X11_fwd_enabled) {
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_FAILURE);
put_uint32(pktout, remid);
pq_push(s->ppl.out_pq, pktout);
ppl_logevent(("Rejected X11 connect request"));
} else {
c = snew(struct ssh1_channel);
c->connlayer = s;
ssh1_channel_init(c);
c->remoteid = remid;
c->chan = x11_new_channel(s->x11authtree, &c->sc,
NULL, -1, FALSE);
c->remoteid = remid;
c->halfopen = FALSE;
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION);
put_uint32(pktout, c->remoteid);
put_uint32(pktout, c->localid);
pq_push(s->ppl.out_pq, pktout);
ppl_logevent(("Opened X11 forward channel"));
}
return TRUE;
case SSH1_SMSG_AGENT_OPEN:
remid = get_uint32(pktin);
/* Refuse if agent forwarding is disabled. */
if (!s->agent_fwd_enabled) {
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_FAILURE);
put_uint32(pktout, remid);
pq_push(s->ppl.out_pq, pktout);
} else {
c = snew(struct ssh1_channel);
c->connlayer = s;
ssh1_channel_init(c);
c->remoteid = remid;
c->chan = agentf_new(&c->sc);
c->halfopen = FALSE;
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION);
put_uint32(pktout, c->remoteid);
put_uint32(pktout, c->localid);
pq_push(s->ppl.out_pq, pktout);
}
return TRUE;
case SSH1_MSG_PORT_OPEN:
remid = get_uint32(pktin);
host = get_string(pktin);
port = toint(get_uint32(pktin));
pf.dhost = mkstr(host);
pf.dport = port;
pfp = find234(s->rportfwds, &pf, NULL);
if (!pfp) {
ppl_logevent(("Rejected remote port open request for %s:%d",
pf.dhost, port));
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_FAILURE);
put_uint32(pktout, remid);
pq_push(s->ppl.out_pq, pktout);
} else {
char *err;
c = snew(struct ssh1_channel);
c->connlayer = s;
ppl_logevent(("Received remote port open request for %s:%d",
pf.dhost, port));
err = portfwdmgr_connect(
s->portfwdmgr, &c->chan, pf.dhost, port,
&c->sc, pfp->addressfamily);
if (err) {
ppl_logevent(("Port open failed: %s", err));
sfree(err);
ssh1_channel_free(c);
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_FAILURE);
put_uint32(pktout, remid);
pq_push(s->ppl.out_pq, pktout);
} else {
ssh1_channel_init(c);
c->remoteid = remid;
c->halfopen = FALSE;
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION);
put_uint32(pktout, c->remoteid);
put_uint32(pktout, c->localid);
pq_push(s->ppl.out_pq, pktout);
ppl_logevent(("Forwarded port opened successfully"));
}
}
sfree(pf.dhost);
return TRUE;
case SSH1_SMSG_STDOUT_DATA:
case SSH1_SMSG_STDERR_DATA:
data = get_string(pktin);
if (!get_err(pktin)) {
int bufsize = seat_output(
s->ppl.seat, pktin->type == SSH1_SMSG_STDERR_DATA,
data.ptr, data.len);
if (!s->stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
s->stdout_throttling = 1;
ssh_throttle_conn(s->ppl.ssh, +1);
}
}
return TRUE;
case SSH1_SMSG_EXIT_STATUS:
{
int exitcode = get_uint32(pktin);
ppl_logevent(("Server sent command exit status %d", exitcode));
ssh_got_exitcode(s->ppl.ssh, exitcode);
s->session_terminated = TRUE;
}
return TRUE;
default:
return FALSE;
}
}
static void ssh1mainchan_succfail_wantreply(struct ssh1_connection_state *s,
int success, void *ctx)
{
chan_request_response(s->mainchan_chan, success);
}
static void ssh1mainchan_succfail_nowantreply(struct ssh1_connection_state *s,
int success, void *ctx)
{
}
static void ssh1mainchan_queue_response(struct ssh1_connection_state *s,
int want_reply, int trivial)
{
sf_handler_fn_t handler = (want_reply ? ssh1mainchan_succfail_wantreply :
ssh1mainchan_succfail_nowantreply);
ssh1_queue_succfail_handler(s, handler, NULL, trivial);
}
static void ssh1mainchan_request_x11_forwarding(
SshChannel *sc, int want_reply, const char *authproto,
const char *authdata, int screen_number, int oneshot)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_X11_REQUEST_FORWARDING);
put_stringz(pktout, authproto);
put_stringz(pktout, authdata);
if (s->local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER)
put_uint32(pktout, screen_number);
pq_push(s->ppl.out_pq, pktout);
ssh1mainchan_queue_response(s, want_reply, FALSE);
}
static void ssh1mainchan_request_agent_forwarding(
SshChannel *sc, int want_reply)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_CMSG_AGENT_REQUEST_FORWARDING);
pq_push(s->ppl.out_pq, pktout);
ssh1mainchan_queue_response(s, want_reply, FALSE);
}
static void ssh1mainchan_request_pty(
SshChannel *sc, int want_reply, Conf *conf, int w, int h)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_REQUEST_PTY);
put_stringz(pktout, conf_get_str(s->conf, CONF_termtype));
put_uint32(pktout, h);
put_uint32(pktout, w);
put_uint32(pktout, 0); /* width in pixels */
put_uint32(pktout, 0); /* height in pixels */
write_ttymodes_to_packet(
BinarySink_UPCAST(pktout), 1,
get_ttymodes_from_conf(s->ppl.seat, conf));
pq_push(s->ppl.out_pq, pktout);
ssh1mainchan_queue_response(s, want_reply, FALSE);
}
static int ssh1mainchan_send_env_var(
SshChannel *sc, int want_reply, const char *var, const char *value)
{
return FALSE; /* SSH-1 doesn't support this at all */
}
static void ssh1mainchan_start_shell(
SshChannel *sc, int want_reply)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_EXEC_SHELL);
pq_push(s->ppl.out_pq, pktout);
ssh1mainchan_queue_response(s, want_reply, TRUE);
}
static void ssh1mainchan_start_command(
SshChannel *sc, int want_reply, const char *command)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_EXEC_CMD);
put_stringz(pktout, command);
pq_push(s->ppl.out_pq, pktout);
ssh1mainchan_queue_response(s, want_reply, TRUE);
}
static int ssh1mainchan_start_subsystem(
SshChannel *sc, int want_reply, const char *subsystem)
{
return FALSE; /* SSH-1 doesn't support this at all */
}
static int ssh1mainchan_send_serial_break(
SshChannel *sc, int want_reply, int length)
{
return FALSE; /* SSH-1 doesn't support this at all */
}
static int ssh1mainchan_send_signal(
SshChannel *sc, int want_reply, const char *signame)
{
return FALSE; /* SSH-1 doesn't support this at all */
}
static void ssh1mainchan_send_terminal_size_change(
SshChannel *sc, int w, int h)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_WINDOW_SIZE);
put_uint32(pktout, h);
put_uint32(pktout, w);
put_uint32(pktout, 0); /* width in pixels */
put_uint32(pktout, 0); /* height in pixels */
pq_push(s->ppl.out_pq, pktout);
}
static void ssh1mainchan_hint_channel_is_simple(SshChannel *sc)
{
}
static int ssh1mainchan_write(SshChannel *sc, const void *data, int len)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_STDIN_DATA);
put_string(pktout, data, len);
pq_push(s->ppl.out_pq, pktout);
return 0;
}
static void ssh1mainchan_write_eof(SshChannel *sc)
{
struct ssh1_connection_state *s =
container_of(sc, struct ssh1_connection_state, mainchan_sc);
PktOut *pktout;
pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH1_CMSG_EOF);
pq_push(s->ppl.out_pq, pktout);
}
static const struct SshChannelVtable ssh1mainchan_vtable = {
ssh1mainchan_write,
ssh1mainchan_write_eof,
NULL /* unclean_close */,
NULL /* unthrottle */,
NULL /* get_conf */,
NULL /* window_override_removed is only used by SSH-2 sharing */,
NULL /* x11_sharing_handover, likewise */,
ssh1mainchan_request_x11_forwarding,
ssh1mainchan_request_agent_forwarding,
ssh1mainchan_request_pty,
ssh1mainchan_send_env_var,
ssh1mainchan_start_shell,
ssh1mainchan_start_command,
ssh1mainchan_start_subsystem,
ssh1mainchan_send_serial_break,
ssh1mainchan_send_signal,
ssh1mainchan_send_terminal_size_change,
ssh1mainchan_hint_channel_is_simple,
};
static void ssh1_session_confirm_callback(void *vctx)
{
struct ssh1_connection_state *s = (struct ssh1_connection_state *)vctx;
chan_open_confirmation(s->mainchan_chan);
}
SshChannel *ssh1_session_open(ConnectionLayer *cl, Channel *chan)
{
struct ssh1_connection_state *s =
container_of(cl, struct ssh1_connection_state, cl);
s->mainchan_sc.vt = &ssh1mainchan_vtable;
s->mainchan_sc.cl = &s->cl;
s->mainchan_chan = chan;
queue_toplevel_callback(ssh1_session_confirm_callback, s);
return &s->mainchan_sc;
}
static void ssh1_rportfwd_response(struct ssh1_connection_state *s,
int success, void *ctx)
{
PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
struct ssh_rportfwd *rpf = (struct ssh_rportfwd *)ctx;
if (success) {
ppl_logevent(("Remote port forwarding from %s enabled",
rpf->log_description));
} else {
ppl_logevent(("Remote port forwarding from %s refused",
rpf->log_description));
struct ssh_rportfwd *realpf = del234(s->rportfwds, rpf);
assert(realpf == rpf);
portfwdmgr_close(s->portfwdmgr, rpf->pfr);
free_rportfwd(rpf);
}
}
struct ssh_rportfwd *ssh1_rportfwd_alloc(
ConnectionLayer *cl,
const char *shost, int sport, const char *dhost, int dport,
int addressfamily, const char *log_description, PortFwdRecord *pfr,
ssh_sharing_connstate *share_ctx)
{
struct ssh1_connection_state *s =
container_of(cl, struct ssh1_connection_state, cl);
struct ssh_rportfwd *rpf = snew(struct ssh_rportfwd);
rpf->shost = dupstr(shost);
rpf->sport = sport;
rpf->dhost = dupstr(dhost);
rpf->dport = dport;
rpf->addressfamily = addressfamily;
rpf->log_description = dupstr(log_description);
rpf->pfr = pfr;
if (add234(s->rportfwds, rpf) != rpf) {
free_rportfwd(rpf);
return NULL;
}
PktOut *pktout = ssh_bpp_new_pktout(
s->ppl.bpp, SSH1_CMSG_PORT_FORWARD_REQUEST);
put_uint32(pktout, rpf->sport);
put_stringz(pktout, rpf->dhost);
put_uint32(pktout, rpf->dport);
pq_push(s->ppl.out_pq, pktout);
ssh1_queue_succfail_handler(s, ssh1_rportfwd_response, rpf, FALSE);
return rpf;
}
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